One of the many great unfairnesses of nature is that girls are often ready for relationships far earlier than boys. My guess is that your guy really likes you but isn’t as ready as you are to take the steps toward a deeper or more exclusive relationship. This has nothing to do with how his mother was as an adult. His dad should know better than to get involved on this level with his teenager’s relationships.
My best suggestion to you is that you slow way, way down. Enjoy your friendship with this fellow and let that friendship deepen and mature. Do fun things together. Hang out with each other’s friends and families. Figure out what you have in common and enjoy it.
Don’t talk about romance. Don’t ask him to swear his love and devotion. That stuff belongs in movies and in relationships that are much further along than yours. If this relationship is meant to be, it will unfold naturally.
I wish you well.